Thanks to those of you who’ve been taking part in these polls. For anyone who’s just turned up, I’ve been trying to collate the best stories from this blog over the last year by asking people to vote in a number of different areas. This is the penultimate one and we’re looking at social science (a fairly broad category, I admit).
It’s a dinosaur tooth, and clearly one that belonged to a predator – sharp and backwards-pointing. But this particularly tooth, belonging to a small raptor called Sinornithosaurus, has a special feature that’s courting a lot controversy. It has a thin groove running down its length, from the root to the very tip. According to a new paper from Enpu Gong of the Chinese Academy of Sciences, it was a channel for venom.
Thanks to a certain film that shall remain nameless, a lot of people probably think that we already know that some dinosaurs are venomous. But the idea that Dilophosaurus was armed with poison, much less spat its toxins at its prey, is non-existent. Some scientists had speculated that they were venomous based on their bizarrely notched and allegedly weak jaws. But these notches have since been found in many other species and no one has ever actually measured the strength of Dilophosaurus‘s jaws.
The best sign that a dinosaur was venomous would be the presence of grooved or hollow teeth. With some notable exceptions, most animals with poison bites use grooves like these to channel their toxins from glands in their mouth to whatever they bite. And grooves are exactly what Gong and his colleagues found in Sinornithosaurus‘s well-preserved skull. Bryan Fry, who discovered venom glands in Komodo dragons earlier this year, says, “It is an absolutely fantastic piece of work. I actually got goose-bumps reading it! Other studies have suggested dinosaurs may be venomous but this is the most solid piece of evidence.”
Sinornithosaurus (meaning “Chinese bird-lizard”) is a small feathered dromaeosaurid (or, more commonly, ‘raptor’) and an early distant cousin of the birds. Its teeth are unusually large and Gong says that those in the upper jaw are “so long and fang-like that the animal appears to be saber-toothed”. They’re very similar to the fangs of back-fanged snakes like boomslangs and vine snakes.
Gong says that other aspects of the skull in support of his venom hypothesis. His team noticed that Sinornithosaurus has a small hollow on the side of its jawbone that could have housed a venom gland. They also found a thin groove running along the animal’s jaw, with small pits at the top of each tooth. They interpret this canal as a “collecting duct” that channelled venom from the gland to the teeth, and each pit could have acted as small, local venom reservoirs. David Burnham, a co-author on the paper, says, “Other fossil animals (dinosaurs, lizards, mammals) have been suggested to be venomous simply on the presence grooved teeth but out work found multiple lines of evidence.”
We’re into the home stretch now. This is the seventh of nine polls where you get to pick your favourite stories of the year from this blog. We’ve had a variety of topics already and today, it’s evolution. Your choices:
Safaris are all about the big game. But even though elephants, leopards and rhinos (oh my!) fill your lens and retinas on a daily basis, it’s still just as wonderful to watch a squirrel scamper through a tree. This species is known in South Africa simply as a tree squirrel, or Smith’s bush squirrel more broadly. Its golden coat with tinges of rust and green make it a far more handsome creature than the common grey squirrels that run through London’s parks. It lacks none of their characteristic agility either, as the video below will demonstrate. I spent a good half-hour watching this individual scurry about the tree that stood right next to the lodge.
This is part six of nine of the NERS poll of the year, in which you good people tell me your favourite stories of the year, as covered in this blog, through the medium of button-clicking. Each poll features a specific scientific discipline, and today neuroscience craves your attention. Your choices:
Exciting hints that scientists had finally discovered the existence of dark matter - the mysterious substance thought to make up a quarter of the Universe – were dashed last night as researchers realised their equipment had detected a dark mattress instead.
The premature announcement was blamed on faulty software. “Apparently, someone left an errant ampersand in our code,” said an embarrassed physicist, before weeping slowly into a whisky glass.
The Cryogenic Dark Matter Search (CDMS) laboratory, buried half a mile underground in an iron mine, announced last night that they had found traces of the weakly-interacting massive particles (or WIMPs) that are thought to make up dark matter.
Instead, they had actually detected a dirty poorly-sprung mattress, left in the cave by a weakly-inebriated, noxious old-timer (or WINO).
“We thought there was around a one in four chance that we had found nothing,” said one of the lead researchers, “but we now know there is a one in one chance that we have found the former sleeping materials of a sheltering vagrant.”
Laboratory technicians were saddened that the most important advance in recent physics had not come to pass, but noted that the dark mattress was really rather comfortable, if not a bit wet.
Those of us who have been on the receiving end of racial abuse know all too well that words can hurt. But they’re also the tip of the iceberg. According to a study of popular US television, we’re exposed to the spectre of racial bias on a regular basis, all without a single word being uttered.
When scenes are muted, body language and facial expressions are enough to convey more negative attitudes towards black characters compared to white ones. This bias is so subtle that we’re largely unable to consciously identify it, yet so powerful that it can sway our own predispositions. In some ways, racial bias acts as a contagion and television as one of its vectors.
These nonverbal cues could have many origins. Actors could act slightly more negatively towards black colleagues, even if they have no explicit racial biases themselves. Their actions could be written into scripts or they may be directed to behave in a certain way, again without any conscious effort on the part of the writers or directors. Whatever the cause, it’s clear that audiences of millions are regularly exposed to very subtle forms of racial bias that can affect their own behaviour.
Max Weisbuch from Tufts University showed volunteers a series of clips taken from episodes of 11 popular shows, including CSI, Grey’s Anatomy, Heroes and House, with an average weekly audience of 9 million Americans. Each show has a racially diverse cast, and Weisbuch focused on an important black character from each show. He chose his clips systematically, taking the first scene where the chosen black character interacted with a white one of roughly equal status within the first, middle and last 5 minute bursts of each episode. Matching for status is important – it obviates the fact that black characters are sometimes less prominent or important to a show.
Weisbuch cut the audio and the featured character from each clip, leaving behind just the reactions of their conversational partner. Each altered clip was shown to 23 white students who had never seen any of the 11 shows. Without any clues from tone of voice or choice of words, the students judged that responses to unseen white characters were significantly more positive than those to unseen black characters.
It’s round five of the Poll of the Year, where you vote in your favourite stories from this blog for 2009. This round – psychology. Here’s a smattering of some of the (in my opinion) coolest, most surprising and, in some cases, most useful, stories of the year. Which do you rate?
In science, we don’t often get to talk about male repression, but a new discovery gives us just such a chance. It turns out that ovaries can only remain ovaries by constantly suppressing their ability to become male. Silence a single gene, and adult ovaries turn into testes. That adult tissues can be transformed in this way would be surprising enough, but doing so by changing a single gene is truly astonishing.
As embryos, our gonads aren’t specific to either gender. Their default course is a female one, but they can be diverted through the action of a gene called SRY that sits on the Y chromosome. SRY activates another gene called Sox9, which sets off a chain reaction of flicked genetic switches. The result is that premature gonads develop into testes. Without SRY or Sox9, you get ovaries instead.
But Henriette Uhlenhaut from the European Molecular Biology Laboratory has found that this story is woefully incomplete. Maleness isn’t just forced onto developing gonads by the actions of SRY – it’s permanently kept at bay by another gene called FOXL2.
The feather is an extraordinary biological invention and the key to the success of modern birds. It has to be light and flexible to give birds fine control over their airborne movements, but tough and strong enough to withstand the massive forces generated by high-speed flight. It achieves this through a complicated internal structure that we are only just beginning to fully understand, with the aid of unlikely research assistants – fungi.
At a microscopic level, feathers are made of a protein called beta-keratin. The same protein also forms the beaks and claws of birds, and the scales and shells of reptiles. It’s close (but less rigid) relative, alpha-keratin, makes up the nails, claws and hairs of mammals. Zoom out, and we see that feathers have a central shaft called the rachis with two vanes on either side. Each vane is composed of barbs that branch off the rachis. Even thinner barbules branch off from the barbs, and are held together by small hooks that give the feather its shape.
What’s much less clear is how the keratin fibres and filaments are organised into the rachis, barbs and barbules. To work that out, scientists would typically slice the rachis in cross-sections and look at it under an electron microscope. But feathers don’t give up their secrets so easily. Their fibres are stuck together with a chemical glue that makes them virtually impossible to separate. Imagine gluing a bundle of matches together and cutting them cross-ways. You could see the fibres that make up the component matches, but if they were glued together tightly enough, you wouldn’t be able to tell where one match started and another began. So it is with feathers and their keratin.
Theagarten Lingham-Soliar from the University of Kwazulu-Natal solved the problem by recruiting fungi as research assistants. He used four species, which like to grow on keratin, to digest the complex molecules that glue individual filaments together. The process was very slow. Even after a year, the feathers seemed in pretty good shape and it was only after 18 months that they had broken down enough to be studied under the microscope.